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Description/Abstract

Migration of offshore seabed waves is hard to measure due to the low migration rates and large measurement errors. Here, sand wave migration rates are determined from the change in the crest position deduced from bathymetric echo-sounding data. The crests are identified as local extremes in a bathymetric profile, after low-pass filtering. This approach is applied to profiles along a pipeline and to 2-dimensional data. A consistent migration rate of several meters per year is found. The accuracy of the estimates is analyzed using markers. The noise in the bed level data is small and does not affect the results, but the errors in the positioning system cause significant errors in the estimates rates. An increase of either the number of surveys or the observation period reduces these errors